/*

 * jccoefct.c

 *

 * Copyright (C) 1994-1995, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains the coefficient buffer controller for compression.

 * This controller is the top level of the JPEG compressor proper.

 * The coefficient buffer lies between forward-DCT and entropy encoding steps.

 */



#define JPEG_INTERNALS

#include "jinclude.h"

#include "jpeglib.h"





/* We use a full-image coefficient buffer when doing Huffman optimization,

 * and also for writing multiple-scan JPEG files.  In all cases, the DCT

 * step is run during the first pass, and subsequent passes need only read

 * the buffered coefficients.

 */

#ifdef ENTROPY_OPT_SUPPORTED

#define FULL_COEF_BUFFER_SUPPORTED

#else

#ifdef C_MULTISCAN_FILES_SUPPORTED

#define FULL_COEF_BUFFER_SUPPORTED

#endif

#endif





/* Private buffer controller object */



typedef struct {

  struct jpeg_c_coef_controller pub; /* public fields */



  JDIMENSION iMCU_row_num;	/* iMCU row # within image */

  JDIMENSION mcu_ctr;		/* counts MCUs processed in current row */

  int MCU_vert_offset;		/* counts MCU rows within iMCU row */

  int MCU_rows_per_iMCU_row;	/* number of such rows needed */



  /* For single-pass compression, it's sufficient to buffer just one MCU

   * (although this may prove a bit slow in practice).  We allocate a

   * workspace of C_MAX_BLOCKS_IN_MCU coefficient blocks, and reuse it for each

   * MCU constructed and sent.  (On 80x86, the workspace is FAR even though

   * it's not really very big; this is to keep the module interfaces unchanged

   * when a large coefficient buffer is necessary.)

   * In multi-pass modes, this array points to the current MCU's blocks

   * within the virtual arrays.

   */

  JBLOCKROW MCU_buffer[C_MAX_BLOCKS_IN_MCU];



  /* In multi-pass modes, we need a virtual block array for each component. */

  jvirt_barray_ptr whole_image[MAX_COMPONENTS];

} my_coef_controller;



typedef my_coef_controller * my_coef_ptr;





/* Forward declarations */

METHODDEF boolean compress_data

    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));

#ifdef FULL_COEF_BUFFER_SUPPORTED

METHODDEF boolean compress_first_pass

    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));

METHODDEF boolean compress_output

    JPP((j_compress_ptr cinfo, JSAMPIMAGE input_buf));

#endif





LOCAL void

start_iMCU_row (j_compress_ptr cinfo)

/* Reset within-iMCU-row counters for a new row */

{

  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;



  /* In an interleaved scan, an MCU row is the same as an iMCU row.

   * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows.

   * But at the bottom of the image, process only what's left.

   */

  if (cinfo->comps_in_scan > 1) {

    coef->MCU_rows_per_iMCU_row = 1;

  } else {

    if (coef->iMCU_row_num < (cinfo->total_iMCU_rows-1))

      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor;

    else

      coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height;

  }



  coef->mcu_ctr = 0;

  coef->MCU_vert_offset = 0;

}





/*

 * Initialize for a processing pass.

 */



METHODDEF void

start_pass_coef (j_compress_ptr cinfo, J_BUF_MODE pass_mode)

{

  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;



  coef->iMCU_row_num = 0;

  start_iMCU_row(cinfo);



  switch (pass_mode) {

  case JBUF_PASS_THRU:

    if (coef->whole_image[0] != NULL)

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    coef->pub.compress_data = compress_data;

    break;

#ifdef FULL_COEF_BUFFER_SUPPORTED

  case JBUF_SAVE_AND_PASS:

    if (coef->whole_image[0] == NULL)

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    coef->pub.compress_data = compress_first_pass;

    break;

  case JBUF_CRANK_DEST:

    if (coef->whole_image[0] == NULL)

      ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    coef->pub.compress_data = compress_output;

    break;

#endif

  default:

    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

    break;

  }

}





/*

 * Process some data in the single-pass case.

 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)

 * per call, ie, v_samp_factor block rows for each component in the image.

 * Returns TRUE if the iMCU row is completed, FALSE if suspended.

 *

 * NB: input_buf contains a plane for each component in image.

 * For single pass, this is the same as the components in the scan.

 */



METHODDEF boolean

compress_data (j_compress_ptr cinfo, JSAMPIMAGE input_buf)

{

  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

  JDIMENSION MCU_col_num;	/* index of current MCU within row */

  JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;

  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

  int blkn, bi, ci, yindex, yoffset, blockcnt;

  JDIMENSION ypos, xpos;

  jpeg_component_info *compptr;



  /* Loop to write as much as one whole iMCU row */

  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;

       yoffset++) {

    for (MCU_col_num = coef->mcu_ctr; MCU_col_num <= last_MCU_col;

	 MCU_col_num++) {

      /* Determine where data comes from in input_buf and do the DCT thing.

       * Each call on forward_DCT processes a horizontal row of DCT blocks

       * as wide as an MCU; we rely on having allocated the MCU_buffer[] blocks

       * sequentially.  Dummy blocks at the right or bottom edge are filled in

       * specially.  The data in them does not matter for image reconstruction,

       * so we fill them with values that will encode to the smallest amount of

       * data, viz: all zeroes in the AC entries, DC entries equal to previous

       * block's DC value.  (Thanks to Thomas Kinsman for this idea.)

       */

      blkn = 0;

      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {

	compptr = cinfo->cur_comp_info[ci];

	blockcnt = (MCU_col_num < last_MCU_col) ? compptr->MCU_width

						: compptr->last_col_width;

	xpos = MCU_col_num * compptr->MCU_sample_width;

	ypos = yoffset * DCTSIZE; /* ypos == (yoffset+yindex) * DCTSIZE */

	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {

	  if (coef->iMCU_row_num < last_iMCU_row ||

	      yoffset+yindex < compptr->last_row_height) {

	    (*cinfo->fdct->forward_DCT) (cinfo, compptr,

					 input_buf[ci], coef->MCU_buffer[blkn],

					 ypos, xpos, (JDIMENSION) blockcnt);

	    if (blockcnt < compptr->MCU_width) {

	      /* Create some dummy blocks at the right edge of the image. */

	      jzero_far((void FAR *) coef->MCU_buffer[blkn + blockcnt],

			(compptr->MCU_width - blockcnt) * SIZEOF(JBLOCK));

	      for (bi = blockcnt; bi < compptr->MCU_width; bi++) {

		coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn+bi-1][0][0];

	      }

	    }

	  } else {

	    /* Create a row of dummy blocks at the bottom of the image. */

	    jzero_far((void FAR *) coef->MCU_buffer[blkn],

		      compptr->MCU_width * SIZEOF(JBLOCK));

	    for (bi = 0; bi < compptr->MCU_width; bi++) {

	      coef->MCU_buffer[blkn+bi][0][0] = coef->MCU_buffer[blkn-1][0][0];

	    }

	  }

	  blkn += compptr->MCU_width;

	  ypos += DCTSIZE;

	}

      }

      /* Try to write the MCU.  In event of a suspension failure, we will

       * re-DCT the MCU on restart (a bit inefficient, could be fixed...)

       */

      if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {

	/* Suspension forced; update state counters and exit */

	coef->MCU_vert_offset = yoffset;

	coef->mcu_ctr = MCU_col_num;

	return FALSE;

      }

    }

    /* Completed an MCU row, but perhaps not an iMCU row */

    coef->mcu_ctr = 0;

  }

  /* Completed the iMCU row, advance counters for next one */

  coef->iMCU_row_num++;

  start_iMCU_row(cinfo);

  return TRUE;

}





#ifdef FULL_COEF_BUFFER_SUPPORTED



/*

 * Process some data in the first pass of a multi-pass case.

 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)

 * per call, ie, v_samp_factor block rows for each component in the image.

 * This amount of data is read from the source buffer, DCT'd and quantized,

 * and saved into the virtual arrays.  We also generate suitable dummy blocks

 * as needed at the right and lower edges.  (The dummy blocks are constructed

 * in the virtual arrays, which have been padded appropriately.)  This makes

 * it possible for subsequent passes not to worry about real vs. dummy blocks.

 *

 * We must also emit the data to the entropy encoder.  This is conveniently

 * done by calling compress_output() after we've loaded the current strip

 * of the virtual arrays.

 *

 * NB: input_buf contains a plane for each component in image.  All

 * components are DCT'd and loaded into the virtual arrays in this pass.

 * However, it may be that only a subset of the components are emitted to

 * the entropy encoder during this first pass; be careful about looking

 * at the scan-dependent variables (MCU dimensions, etc).

 */



METHODDEF boolean

compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf)

{

  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

  JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;

  JDIMENSION blocks_across, MCUs_across, MCUindex;

  int bi, ci, h_samp_factor, block_row, block_rows, ndummy;

  JCOEF lastDC;

  jpeg_component_info *compptr;

  JBLOCKARRAY buffer;

  JBLOCKROW thisblockrow, lastblockrow;



  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

       ci++, compptr++) {

    /* Align the virtual buffer for this component. */

    buffer = (*cinfo->mem->access_virt_barray)

      ((j_common_ptr) cinfo, coef->whole_image[ci],

       coef->iMCU_row_num * compptr->v_samp_factor,

       (JDIMENSION) compptr->v_samp_factor, TRUE);

    /* Count non-dummy DCT block rows in this iMCU row. */

    if (coef->iMCU_row_num < last_iMCU_row)

      block_rows = compptr->v_samp_factor;

    else {

      /* NB: can't use last_row_height here, since may not be set! */

      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);

      if (block_rows == 0) block_rows = compptr->v_samp_factor;

    }

    blocks_across = compptr->width_in_blocks;

    h_samp_factor = compptr->h_samp_factor;

    /* Count number of dummy blocks to be added at the right margin. */

    ndummy = (int) (blocks_across % h_samp_factor);

    if (ndummy > 0)

      ndummy = h_samp_factor - ndummy;

    /* Perform DCT for all non-dummy blocks in this iMCU row.  Each call

     * on forward_DCT processes a complete horizontal row of DCT blocks.

     */

    for (block_row = 0; block_row < block_rows; block_row++) {

      thisblockrow = buffer[block_row];

      (*cinfo->fdct->forward_DCT) (cinfo, compptr,

				   input_buf[ci], thisblockrow,

				   (JDIMENSION) (block_row * DCTSIZE),

				   (JDIMENSION) 0, blocks_across);

      if (ndummy > 0) {

	/* Create dummy blocks at the right edge of the image. */

	thisblockrow += blocks_across; /* => first dummy block */

	jzero_far((void FAR *) thisblockrow, ndummy * SIZEOF(JBLOCK));

	lastDC = thisblockrow[-1][0];

	for (bi = 0; bi < ndummy; bi++) {

	  thisblockrow[bi][0] = lastDC;

	}

      }

    }

    /* If at end of image, create dummy block rows as needed.

     * The tricky part here is that within each MCU, we want the DC values

     * of the dummy blocks to match the last real block's DC value.

     * This squeezes a few more bytes out of the resulting file...

     */

    if (coef->iMCU_row_num == last_iMCU_row) {

      blocks_across += ndummy;	/* include lower right corner */

      MCUs_across = blocks_across / h_samp_factor;

      for (block_row = block_rows; block_row < compptr->v_samp_factor;

	   block_row++) {

	thisblockrow = buffer[block_row];

	lastblockrow = buffer[block_row-1];

	jzero_far((void FAR *) thisblockrow,

		  (size_t) (blocks_across * SIZEOF(JBLOCK)));

	for (MCUindex = 0; MCUindex < MCUs_across; MCUindex++) {

	  lastDC = lastblockrow[h_samp_factor-1][0];

	  for (bi = 0; bi < h_samp_factor; bi++) {

	    thisblockrow[bi][0] = lastDC;

	  }

	  thisblockrow += h_samp_factor; /* advance to next MCU in row */

	  lastblockrow += h_samp_factor;

	}

      }

    }

  }

  /* NB: compress_output will increment iMCU_row_num if successful.

   * A suspension return will result in redoing all the work above next time.

   */



  /* Emit data to the entropy encoder, sharing code with subsequent passes */

  return compress_output(cinfo, input_buf);

}





/*

 * Process some data in subsequent passes of a multi-pass case.

 * We process the equivalent of one fully interleaved MCU row ("iMCU" row)

 * per call, ie, v_samp_factor block rows for each component in the scan.

 * The data is obtained from the virtual arrays and fed to the entropy coder.

 * Returns TRUE if the iMCU row is completed, FALSE if suspended.

 *

 * NB: input_buf is ignored; it is likely to be a NULL pointer.

 */



METHODDEF boolean

compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)

{

  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;

  JDIMENSION MCU_col_num;	/* index of current MCU within row */

  int blkn, ci, xindex, yindex, yoffset;

  JDIMENSION start_col;

  JBLOCKARRAY buffer[MAX_COMPS_IN_SCAN];

  JBLOCKROW buffer_ptr;

  jpeg_component_info *compptr;



  /* Align the virtual buffers for the components used in this scan.

   * NB: during first pass, this is safe only because the buffers will

   * already be aligned properly, so jmemmgr.c won't need to do any I/O.

   */

  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {

    compptr = cinfo->cur_comp_info[ci];

    buffer[ci] = (*cinfo->mem->access_virt_barray)

      ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],

       coef->iMCU_row_num * compptr->v_samp_factor,

       (JDIMENSION) compptr->v_samp_factor, FALSE);

  }



  /* Loop to process one whole iMCU row */

  for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;

       yoffset++) {

    for (MCU_col_num = coef->mcu_ctr; MCU_col_num < cinfo->MCUs_per_row;

	 MCU_col_num++) {

      /* Construct list of pointers to DCT blocks belonging to this MCU */

      blkn = 0;			/* index of current DCT block within MCU */

      for (ci = 0; ci < cinfo->comps_in_scan; ci++) {

	compptr = cinfo->cur_comp_info[ci];

	start_col = MCU_col_num * compptr->MCU_width;

	for (yindex = 0; yindex < compptr->MCU_height; yindex++) {

	  buffer_ptr = buffer[ci][yindex+yoffset] + start_col;

	  for (xindex = 0; xindex < compptr->MCU_width; xindex++) {

	    coef->MCU_buffer[blkn++] = buffer_ptr++;

	  }

	}

      }

      /* Try to write the MCU. */

      if (! (*cinfo->entropy->encode_mcu) (cinfo, coef->MCU_buffer)) {

	/* Suspension forced; update state counters and exit */

	coef->MCU_vert_offset = yoffset;

	coef->mcu_ctr = MCU_col_num;

	return FALSE;

      }

    }

    /* Completed an MCU row, but perhaps not an iMCU row */

    coef->mcu_ctr = 0;

  }

  /* Completed the iMCU row, advance counters for next one */

  coef->iMCU_row_num++;

  start_iMCU_row(cinfo);

  return TRUE;

}



#endif /* FULL_COEF_BUFFER_SUPPORTED */





/*

 * Initialize coefficient buffer controller.

 */



GLOBAL void

jinit_c_coef_controller (j_compress_ptr cinfo, boolean need_full_buffer)

{

  my_coef_ptr coef;



  coef = (my_coef_ptr)

    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

				SIZEOF(my_coef_controller));

  cinfo->coef = (struct jpeg_c_coef_controller *) coef;

  coef->pub.start_pass = start_pass_coef;



  /* Create the coefficient buffer. */

  if (need_full_buffer) {

#ifdef FULL_COEF_BUFFER_SUPPORTED

    /* Allocate a full-image virtual array for each component, */

    /* padded to a multiple of samp_factor DCT blocks in each direction. */

    int ci;

    jpeg_component_info *compptr;



    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;

	 ci++, compptr++) {

      coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)

	((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,

	 (JDIMENSION) jround_up((long) compptr->width_in_blocks,

				(long) compptr->h_samp_factor),

	 (JDIMENSION) jround_up((long) compptr->height_in_blocks,

				(long) compptr->v_samp_factor),

	 (JDIMENSION) compptr->v_samp_factor);

    }

#else

    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

#endif

  } else {

    /* We only need a single-MCU buffer. */

    JBLOCKROW buffer;

    int i;



    buffer = (JBLOCKROW)

      (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,

				  C_MAX_BLOCKS_IN_MCU * SIZEOF(JBLOCK));

    for (i = 0; i < C_MAX_BLOCKS_IN_MCU; i++) {

      coef->MCU_buffer[i] = buffer + i;

    }

    coef->whole_image[0] = NULL; /* flag for no virtual arrays */

  }

}

